Question

12. With significant effort(!), an ordinary person on a bicycle can
produce about 250 watts of electricity on a stationary bicycle. A
company, in order to encourage physical fitness while at the same
time conserving electrical energy, is requiring employees to heat
up their cup of hot beverage by the use of an electrical heater
powered by a stationary bicycle generator. How long does the
employee have to pedal the bicycle to heat 250 grams (a small cup)
of water from 20 C to 80 C?